Reverse arm brake



Oct. 25, 1966 w. w. PLUMB REVERSE ARM BRAKE Filed Sept. 28, 1964 INVENTOR WILLIAM w. PLuMs United States Patent 3,281,043 REVERSE ARM BRAKE William W. Plumb, Dallas, Tex., assignor to St. Regis Paper Company, New York, N.Y., a corporation of New York Filed Sept. 28, 1964, Ser. No. 399,552 2 Claims. (Cl. 226-495) This invention relates to a braking device which permits the movement of a sheet material in one direction and prohibits the movement of said sheet material in the opposite direction.

In the paper and packaging industries, sheet or film stock in the form of rolls or individual flat sheets is fed through a variety of machines for processing, printing, packaging and other necessary operations. The aforesaid materials, hereinafter called sheet material, may comprise, paper, cellophane, polyolefin films, vinyl films, wax paper, foils, laminates and the like. In many cases, it is desirable that the flow of sheet material at various points in the machines be controlled in such a manner that the material can move in one direction only. This control is particularly important in those operations that are intermittent, requiring proper positioning of each succeeding portion of the sheet material and also in continuous operations wherein tension would cause the backward movement of said sheet material in the event of a break.

A number of brakes for use with sheet material are known in the industry. One such typical brake is used in a slideable relation to the sheet material and comprises a weighted eccentric arm rotatable on a shaft, said arm having a rubber covering and so placed that when moving the sheet material forward, it can slide in relation to the rubber and a backing plate or roller over which the sheet material moves. Any tendency of the sheet material to move rearward, due to its weight or tension, causes the nip formed by the rubber covering and the backing plate or roller to seize said sheet material. This type of brake is deficient in that, by virtue of its slideable relation with the sheet material, dragging over said material causes marks 'or other defects on the surface of the sheet material.

Another type brake comprises a roller with an attached ratchet, and a ratchet arm which permits movement of the roller in one direction only. The vertical component of force as determined by the weight of the brake acting on the sheet material against a roller or backing plate creates the necessary friction between the roller and the sheet material, thereby preventing unlimited backward movement of said sheet material when the ratchet arm engages the teeth of the ratchet. The amount of backward movement permitted by this type brake is dependent upon the dimensions and the number of ratchet teeth. The sheet material can move backward an amount equal to the distance between the teeth of said ratchet. The mechanically complex ratchet type brake is relatively costly and requires excessive maintenance and replacement.

It is an object of this invention to provide a simple reverse arm brake which will not mark or deface the sheet material.

It is also an object of this invention to provide for a brake that will eliminate all backward movement of said sheet material.

Another object of this invention is to provide for a low-cost, mechanically simple brake which can be easily and inexpensively maintained in proper operating condition.

This invention comprises a resilient disc, or a disc having a resilient peripheral surface, rotatably mounted on an arm and a sharp-edged pawl which is freely pivoted on a pin attached to said arm which slides on the periphery of said disc when said disc is rotated in one direction but whose sharp edge engages said rubber tire when an attempt is made to rotate said disc in the opposite direction and thus operates on the principle of an infinitely variable ratchet. This invention is further explained by reference to the accompanying drawings.

FIG. 1 is a bottom plan view of said brake with parts in section.

FIG. 2 is a side view of the brake.

FIG. 3 is an enlarged fragmentary view illustrating the pin on which the pawl is mounted, and is a section on the line 33 of FIG. 2.

In the above figures, number 10 represents the arm to which the disc 11 is rotatably attached by pin 12. A resilient tire 13 of rubber, plastic, leather, woven or felted fabric or the like is mounted on disc 11. Pawl 14 having pointed edge portion or arm 16 and a weighted end portion or arm 30 is pivotally mounted to arm 10 by pin 15. Pin 15 is comprised of shaft 28 and an eccentric threaded end 29 which permits adjustment of the pivot point for pawl 14, allowing for optimum positioning of sharp edge 16. The pivot point of pawl 14 is so located that said pawl tends to rotate by gravity in a clockwise direction about said pivot point. Stop pin 21 is mounted on arm 10 to prevent inadvertent rotation of pawl 14 beyond the operating limits set thereby. Stop pin 20 is used in a similar fashion to prevent excessive rotation of pawl 14 in the counter-clockwise direction. Sheet material 17 when fed over idler rolls 18 and 19 in the direction shown by the arrows causes the disc to rotate in a clockwise direction. A back-up plate, not shown, can be used in place of idler roll 19. Movement of sheet material 17 in a direction opposite to the arrows causes the pointed edge 16 of pawl 14 to engage the resilient tire 13 and thereby prohibits the rotation of disc 11, the distance between the pointed end of arm 16 and its pivot center 15 being greater than the distance between said pivot center and the intersection of a line extending therefrom normal to a tangent of said disc surface. The nip action between the tire 13 and idler roll 19 (or back-up plate) prevents the backward movement of the sheet material. Arm 10 is freely pivoted on shaft 22 of the machine to which the reverse arm brake is attached.

Number 23 represents a ball bearing which permits the free rotation of disc 11 on pin 12. Number 24 is a bearing retainer ring and collar 25 locates and prevents disc 11 from contacting arm 10. Spacer 26 is used to position pawl 14 so that it properly contacts the periphery of resilient tire 13. Lips 27 on disc 11 are made to retain the tire 13 in the correct lateral position on said disc. The height of the lips 27 is such as to provide for easy removal and replacement of tire 13.

The tire is preferably made of gum rubber, having a Shore A hardness in the range of 50 to 60.

The reverse arm brake can be operated at any angle as long as the center of gravity of pawl 14 causes sharp edge 16 to maintain contact with the resilient tire 13. In the event that it is desired to operate the reverse arm brake in positions other than described above, a spring (not shown) can be used to provide for the clockwise rotational force on pawl 14 to maintain a contact with the tire 13. In addition, a spring (not shown) can be used on arm 10 to provide the force necessary to maintain the tire in contact with the idler roll 19 or a backing plate.

I have illustrated and described a preferred form of my invention. It will be apparent to anyone skilled in the art that many changes in details of construction and proportions of the parts are possible.

I claim:

1. A braking device comprising an arm freely pivoted adjacent one end about a fixed axis, a smooth resilient surfaced wheel freely rotatable and attached to said arm adjacent its opposed end and adapted to rest by gravity on a forwardly moving sheet disposed beneath said Wheel, a sharp-edged pawl pivotable about a pin attached to said arm, the sharp edge of said pawl being in a 'slideable relation to said wheel surface when said Wheel is rotated in one direction and said sharp edge engaging the periphery of said wheel and preventing movement thereof when an attempt is made to rotate the wheel in the opposite direction, the pawl being eccentric about its pivot point whereby the force of gravity maintains the sharp edge of said pawl in contact with the periphery of the wheel.

2. A braking device in accordance with claim 1 in Which the resilient tire consists of gum rubber having a Shore A hardness of 50 to 60.

References Cited by the Examiner UNITED STATES PATENTS 747,865 12/1903 Dexter et a1. 271-19 911,132 2/1909 Kleidmann 27143 1,748,023 2/1930 Lutz et al. 18882.7 2,042,734 6/1936 Roy 2712l FOREIGN PATENTS 582,511 8/1933 Germany. 498,453 1/ 1939 Great Britain.

M. HENSON WOOD, JR., Primary Examiner.

ALLEN N. KNOWLES, Examiner. 

1. A BRAKING DEVICE COMPRISING AN ARM FREELY PIVOTED ADJACENT ONE END ABOUT A FIXED AXIS, A SMOOTH RESILIENT SURFACED WHEEL FREELY ROTATABLE AND ATTACHED TO SAID ARM ADJACENT ITS OPPOSED END AND ADAPTED TO REST BY GRAVITY ON A FORWARDLY MOVING SHEET DISPOSED BENEATH SAID WHEEL, A SHARP-EDGED PAWL PIVOTABLE ABOUT A PIN ATTACHED TO SAID ARM, THE SHARP EDGE OF SAID PAWL BEING IN A SLIDABLE RELATION TO SAID WHEEL SURFACE WHEN SAID WHEEL IS ROTATED IN ONE DIRECTION AND SAID SHARP EDGE ENGAGING THE PERIPHERY OF SAID WHEEL AND PREVENTING MOVEMENT THEREOF WHEN AN ATTEMPT IS MADE TO ROTATE THE WHEEL IN THE OPPOSITE DIRECTION, THE PAWL BEING ECCENTRIC ABOUT ITS PIVOT POINT WHEREBY THE FORCE OF GRAVITY MAINTAINS THE SHARP EDGE OF SAID PAWL IN CONTACT WITH THE PERIPHERY OF THE WHEEL. 